Source? The computer is programmed by humans, it begs to reason that it's going to be influenced by the human instructions. It's not that you can't tell who is genetically related to who by appearance, that's not the argument. It's a simple apparent fact that offspring often resemble their parents and given enough time and separation populations will develop various common traits within their population.

Race is by its nature a spectrum of sorts, though I loath the term because it implies some linear criteria one can measure where race is far more complicated. But I digress, we can take simple skin color as the criteria. And we can say people have more or less melanin. At what point do we draw the line of separation? That is socially decided.

In the same way different cultures look at the color spectrum and group colors differently in their own languages. To say that the physical reality of color, as electromagnetic radiation, is somehow a social construct would be lunacy. But exactly what shades of a color you determine to be "blue" or "green" is a social construct. Humans don't think in terms of wavelengths of light but in associations with things.

Many cultures have a tendency to combine the colors of blue and green into a singular concept of a "natural" color. Most cultures didn't have a word for Orange until people started to import the fruit. Which is why they share the word. The orange isn't named after its color, rather the color was named after the fruit, we teach that there are usually 6 colors in kindergarten. There's actually an "infinite" number of colors, but how you want to precisely define the difference is pointless, and generally falls along what our own social conditioning tells us to sort them.

Another good example is animals. Rats and mice are clearly different, yet go to some countries and the word for both is the same. Hell even the number of continents on earth is somewhat of a "social construct" since how we define the term is important. Kids in countries in Asia learn there are 5, Westerners learn there are 6. In actuality they are both right and both wrong. There's as many continents as there are land masses. But the Americas and Afro-Eurasia are just as easily considered to be two giant continents, or perhaps one if you disregard the bearing straight but I'll digress.

A lot of or understanding of classifications is in fact due to how we define things. And a lot of the time even our understanding of purely natural phenomenon can become entangled with various social concepts and indeed, constructs.

So I propose a simple yet extremely difficult question. What is an objective criteria by which we can sort people into different racial groups? And why is that criteria the best criteria?